Extension crashes repeatedly when includePath contains non-folder paths in it

[bobbrow]

Starting with 0.17.0-insiders, a bug was introduced that will cause the extension to repeatedly crash if a non-folder path was added to the includePath in c_cpp_properties.json.

For example:

    "includePath": [
        "${workspaceFolder}/include/my_header_file.h"
    ]

should be just:

    "includePath": [
        "${workspaceFolder}/include"
    ]

If you actually meant to force include the file everywhere, then use the forcedInclude property.